A comparative study of natural pozzolan and fly ash: Investigation on abrasion resistance and transport properties of self-consolidating concrete

Abstract

• Potential for use of natural pozzolans in self-consolidating concrete (SCC) was investigated. • Performance of natural pozzolan and fly ash in self-consolidating concrete was compared. • Mechanical and transport properties, drying shrinkage, and abrasion resistance of concrete were investigated. • Natural pozzolans performed at the same level of fly ash showing a proper replacement for fly ash in SCC. This study compared the influence of natural pozzolan with fly ash, as Supplementary Cementitious Material (SCMs), on properties of Self-Consolidating Concrete (SCC) with particular focus on abrasion resistance and transport properties. Natural pozzolan and fly ash replaced a portion of portland cement at the levels of 0, 15, 22.5, 30, and 37.5% by mass. A set of comprehensive experimental program was devised to measure fresh properties (slump flow, J-ring, T 50 and U-box), mechanical properties (compressive strength and modulus of elasticity), drying shrinkage, transport properties (rapid chloride penetration and rapid chloride migration tests, water permeability and absorption, and capillary water absorption) and depth of wear. Overall, the results indicated that replacing 15 and 22.5% of portland cement with SCM, decreased final depth of wear for SCC mixes. However, the observed improvements were diminished with increases in dosage of SCM. Use of SCMs led to similar or improved performance in terms of mechanical and transport properties, specifically at later ages of curing, showing potential for use of fly ash and natural pozzolan in SCC. Considering all the tests carried out, natural pozzolan performed at the same level of fly ash showing its great potential for use in SCC to achieve the same performance. This is of great importance considering the shortage of fly ash in recent years.